Synthesis and characterization of surface oxide films on CoGa(100)

It has been shown that a Ga₂O₃ film forms on the surface of CoGa alloy crystals when exposed to oxygen (Pan, 2001 and Vlad, 2010). In this work we report the results of the characterization of surface oxides on CoGa(100) using X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), and ion scattering spectroscopy (ISS). The oxides were synthesized using either O₂ or NO₂ as the oxidant at 300 K or in excess of 700 K. ISS scans showed that cobalt was always present in the top surface layer regardless of oxidation conditions. XPS showed that depending on the oxidant and the temperature, the composition of the oxide films vary depending on oxidation treatment, with some oxides being nearly all Ga₂O₃ and ordered with a sharp LEED pattern consisting of (2 × 1) domains rotated by 90° and others being Co-Ga mixed oxides that gave no diffraction pattern.